Process of extracting iodine from aqueous solutions



C. W. JONES July 11, 1933.

PROCESS OF EXTRACTING IODINE FROM AQUEOUS SOLUTIONS Filed Feb. 25, 1928 QUE:

Patented July 11, 1933 UNITED STATES lelaeee PATEN eerie 7 Z- GOULTER w. JONES, or MIDLAND, ICHIGAN, AssIeNoP. TO JONES CHEMICAL f COMPANY, INCORPORATED, or MCDADE, LOUISIANA, A. oonrone'rron or LOUISIANA PROCESS OF EXTRAOTING IODENE FROM AQUEOUS SOIJTJ'TIONS,

Application filed February 23, 1928. Serial No. 255,237.

This invention relates to a novel process for the extraction of iodine from aqueous solutions, and is particularly applicable to the extraction of comparatively small amounts of iodine from mineral waters, natural brines, and mother liquors resulting from the partial removal of the saline contents from salt water or natural brine. These solutions usually contain iodine compounds 10 in very small proportions, and it would not be economically practical to evaporate large quantities of water, or to handle a large tonnage of low-priced salts in order to recover a comparatively small amount of iodine.

Mineral waters, brines, and mother liquors of the United States are not, to my knowledge, at present being worked for the recovery of iodine, and'I am not aware that a successful method has been developed that will profitably recover their small iodine content. By my improved process, the great er part of the comparatively small amount of iodine found in mineral waters, brines,

and mother liquors may be economically recovered without preliminary concentration of the aqueous solution or the removal of other products therefrom.

According to my improved process, the extraction of iodine from aqueous solutions is so accomplished, first, by treating the solution in a manner to free the iodine from itschemical combinations without thereby liberating other substances which will militate against its existence in the free state. The

liberated iodine dissolves in the aqueous so:

lution and is removed therefrom by bringing in contact with the solution containing the iodine a current of an inert gas which has the property of taking up and carrying 40 off the iodine from the solution. The iodineladen gas is then brought in contact with a suitable absorbent or reagentwith which the iodine reacts to form an iodine compound. From the resultant iodine compound, solid iodine or iodides may be prepared in well known ways.

By the term inert gas as herein used is meant any gas or mixture of gases that do not react with the iodine to, form a compound. Examples of inert gases that may entering the tower at the bottom thereof be used are steam, oxygen, nitrogen, air, and carbon dioxide. The above gases are given by way of illustration. There are, however, many other inert gases that mightbe used. By preference, I use air for purposes of economy. c

The iodine is first liberated'from its com- V solutions, for example, can be used to free the iodine; and where the solution happens to be initially basic, it may be neutralized or slightly acidified for the treatment. If preferred, the liberation may be accomplished electrolytically. The process is practically the'same whether caused by the addition of a chemical agent, as above described, or by electrolytic decomposition of the salts in the solution. For the purpose of illustration, I will describe the process in which-chlorine is used for the purpose of thus liberatingthe iodine. Y .7

In the accompanying drawing, I have illustrated diagrammatically a form of apparatus which may be employed in practicmg my process. .7

Thenumeral 1 indicates a'tank for containing the aqueous solution from which iodine is to be liberated. The solution is supplied to the tank from any 'suitable'source by means of a pipe 2. Leading out from. the

bottom of tank l-is a pipe 3 which is passed through the top of an enlongated tank or tower l, and within said tower and near the top thereof is provided with a spray nozzle 5 for spraying the solution soasto bringlit in intimate contact with air or other inert gas through a pipe 6. The numeral 7 indicates a combined suction fan and blower, the inlet to which, indicated by 8, communicates with. a second tower 9 at a suitable distance above the bottom thereof. A pipe 1.0 isconnected to and communicates with the towers a and 9 at the upper ends thereof. The numeral 11 indicates a pump which communicates with the tower 9 near the base thereof through the medium of a valve 18 and averti'calpipe 13 leading to the bottom of the pump. From the upper end of the pump a pipe 14: passes through the top of tower 9 and is provided on its end within the tower and near the upper end of the latter with a spray nozzle 15. The numeral 16 indicates a cylinder-contain- 7 ing liquid chlorine under "pressure,'which is supplied to the tank 1 through pipe 17 to dissolve in the aqueous solution therein;

In practicing, the invention, the aqueous solution, which may be a mineral water, a natural brine,- or mether: liquor, is continuously supplied to the tank 1 through pipe 2, and at the same time the chlorine is admitted into the bottom of tank 1 through the pipe 17 so as to sufliciently oxidize the solution to liberate substantially all of the iodine from its combinations. Assuming. the iodine to be combined with the metal sodium, the reaction occurring would be expressed by the following formula:

2NaI C1 =2NaC1+ I; The oxidized solution containing the dissolved iodine passes out of the tank through pipe 3-and is delivered into the tower 4, preferablyin the form of a spray, and descend ing therein is brought into intimate contact with a rising volume of air or other inert gas entering the tower through pipe 6. Such air or inert gas will remove the dissolved iodine and the iodine-laden air or gas passes out of tower 4 through pipe 10 and into the tower 9 Where it comes in contact with'a continuous spray of a suitable alkaline solution, suclras soda lye or as indicated below. soda ash which will absorb the iodine from-the air. The reaction occurring in the tower 9 may be expressed by. the following formula:

The alkaline solution is initially'supplied to the tower 9 and is continuously pumped therefrom and circulated through said. tower in the form of a. spray, as previously described, until the greater part of its alkaline content has been neutralized by the iodine. When this occurs, the pump 11 may be stopped, valves 18 and 19 in the pipe 12 opelled, and the iodide liquor run out of tower 9, after which a fresh supply of the alkaline solution would be supplied to the tower though the pipe 12 and the valve 19 closed, and the pump again started. The iodide solution removed from tower 9 will then be treated in well known ways to produce commercial iodine or iodides. The aqueous solution falling to the bottom of tower 4' continuously drains therefrom through a pipe 20 and may, ifdesired, pass directly to the sewer. If preferred, the air in tower 9 from which the 'iodine has'been removed may be recirculated through the tower 4, and when this is done, the pipe 6 will communicate directly with the blower 7, as shown by full lines in the drawing. Otherwise, as shown by dotted lines, the used air from tower 9 could be discharged into the atmosphere and a fresh supply of air be continuously drawn in through pipe 6. In the latter operation, fresh air will be drawn in through pipe 6 by suction caused I have chosen to illustrate the oxidation step as taking place in tank 1, but this step may be accomplished in the blowing-out tower-d by ((1) adding solution containing an oxidizingagent along with the iodinecontaining solution; and (b) chlorine -or bromine gas, or, other suitable oxidizing reagentsmay be added to the iodine-containing solution inthe tower at any suitable point between the top and bottom thereof.

The oxidation of the iodine-containing solution should; be sullieient in extent to liberatesubstantially all? iodine and, in addition, to oxidize any ferrous salts, sulphur, and other analogouscompounds to a degree that they willnot reduce the liberated iodine. 1 have found that oxidation appreciably in eX- cess of the limits above stated is objectionable; for example, such'oxidizing agents as chlorine or bromine, when used in excess,

will rapidly convert the liberated iodine to hypo-iodites and iodates, in which combinations the-iodine cannot be blown out.

The above described process may be operated at, above, or below, atmospheric pressure, nor is the temperature range limited. J

However, it isobvious that with any particu lar inert gas used, there are certain pressure and temperature ranges necessary to observe in order to maintain it in the gaseous form.

Iclaimz I 1. A process of recovering iodine from aqueous solutions containing iodine compounds,- which includes the steps of liberatingthe iodine from'its chemical combinations therein, and blowing air through such solution while disseminated and without-sub'stai'itial increase in temperature, to extract the liberated iodine therefrom. a r c 2. A process of recovering iodme'from aqueous solutions containing iodine com pounds, which includes thesteps of liberatingtheiodine from its chemical combinations therein, and opposing a stream of such solution in finely divided form and at a temperature approximating that of natural brine, with-a stream of an inert gas nonconden'sable at room temperature, whereby the liberated iodine is blown out. V

3. A process of recovering iodine from aqueous solutions containing iodine compounds, which includes the steps of liberating the iodinefrom its chemical combinations thereln, and opposing a stream of such solution in'filiely divided form and at a temperature r approximating that of natural brine,with a stream of air, whereby the liber ated iodine isbl'own out.

4.'The process of recovering iodine from nonfalkaline aqueous solutions containing odlne compounds, whichcomprises liberating the iodine from its chemical combinations therein, by treating with a more active halogen, and bringing at approximately the same temperature the resulting dissolved iodine contaming aqueous solution in disseminated form intoeontact With astream of air, whereby the liberated-iodine is blown out.

5.'The process of recovering iodine from non-alkaline aqueous solutions containing iodine compounds, which comprisesliberating the iodinefron1 its chemical combinations therein by treating with chlorine, bringing at approximately the same temperature the resulting dissolved iodine containing aqueous solution in "disseminated form into contact with a stream of air, whereby theliberated iodine isblown out. i I f f 6. A process of recovering iodine from aqueous solutions containing iodine compounds, which includes the steps of liberating theiodine from its chemical combinations therein, blowing an inert gas non-conde'n sable atroom temperature through a stream of said solution in finely divided form and without substantialincrease in temperature, to extract the liberated iodine therefrom, and then'passing 'such gas in parallel flow contact with a finely divided stream of an alkaline absorbing agent for iodine.

7 A process of recovering. iodine from aqueous solutions containing iodine compounds, which includes the steps of liberatingthe iodine from its chemical combinations therein, blowing air through a stream of said solution in 'finely divided form and at approximately natural brine temperature, to extract the liberated iodine therefrom, and then passing such gas in parallel flow contact with a finely divided stream of an alkaline absorbing agent for iodine.

8. The process of recovering iodine from slightly acid aqueous solutions containing iodine compounds, which comprises liberating the iodine from its chemical combinations therein, without substantial change in temperature bringing the dissolved iodine containing aqueous solution-in ldisseminated form into contact with air to extract the iodine therefrom, and "then contacting the iodine-laden gas with an absorbing agent.

9. The proc essof recovering iodine from non-alkaline aqueous solutions containing iodine compounds, which comprisesliberat ing the iodine from its chemical combinations therein oxidizing the solution to an.'ex-= tent suflicient to liberate substantially allof the iodine content but avoiding an appreciable-"excess of oxidatiombringing in disseminated form the aqueous solution contain ing thefdissolved iodine, without substantial increasein temperature, into contact with an inert gas non-condensable at roomtemperature,toextract the iodine-tl1erefrom,and then contacting the iodine-laden gasjwith an ab sorbing agent forming an iodine compound.

10. The process of recovering iodine: from non-alkaline aqueous solutions containing the iodine-laden gas with an alkaline absorbing agent forming aniodine'compound,

and recoveringthe iodine from suchcome pound;

11. The process ofrecovering iodine from aqueous solutions containing iodine compounds, which includes the S CQpS Ol liberating the iodinefrom its chemical combinations therein by oxidizing the solution to anextent suflicient to s liberate substantially all the iodine content but avoiding an appreciable excess of oxidation, brlnging the solutlon containing the dissolved iodine at approximatelyinaturalbrine temperature and in' the form of a finely divided stream, against a current of air whereby such iodine is blown out, and then contactmg the iodlne-laden air with an absorbing agent capable of forming a compound with such iodine.

12. The process of recovering iodine from aqueous solutions containing iodine compounds, which includes the steps of liberating the iodine from its chemical combinations therein by oxidizing the solution to an extent sufiicient to liberate substantially allthe iodine content but avoiding an appreciable excess of oxidation, bringing the solution containing the dissolved iodine at approximately natural brine temperature and in the form of a finely divided stream against a current of air whereby such iodine is blown out, and

then passing the iodine-laden air in parallel flow contact with a finely divided-';strean1-;of an alkaline absorbing; agent capable of form ing a compound with SllChaiOdiIlG. a 1 V 13. The process of recovering iodine from non-alkaline aqueous solutions containing io dine compounds, which consists in liberating the iodine from its chemical combinations therein, disseminating: and bringing said aqueous solutioncontaining the dissolved iodine without substantial increase in temperature in countercurrent contact with an inert gas-non-condensable at room temperature to extract theiodine therefrom, then causing the iodine-laden gasto come incontact with asuitable absorbingandcombining agent for the iodine, thereby forming an iodide compound=,and-. then recovering the iodine from such compound in the form of commercial iodine or iodides. A

14. The process of recovering iodine from non-alkaline aqueous solutions containing iodine compounds, which comprises liberating the iodine. from its chemical. combinations therein, without substantial change in tems perature bringing the dissolved iodine vcontaining aqueous solution in disseminated form into contact with an inert gas non-condensable at room'temperat-ure to extractthe iodine therefrom, and then contacting the iodinedadengas with an" absorbing agent selected from the group consisting: of alkali carbonates, alkalihydroxides, alkaline earth hydroxides; 1

15. The process of recovering iodine-from non-alkaline aqueous solutions containing iodine compounds, whichzcomprises .hbera-ttions? therein, without substantial change in temperature "bringing the dissolved iodine containing aqueous solution in disseminated form, into contact with air to: extract iodine therefrom, and then contacting,- the iodine-laden .gaswith sodium carbonate,

, ;'1"(. ;The process of recovering iodine from non-alkaline, aqueous solutions containing iodine compounds, which; comprises liberattheiiodin'e. from its chemical. combinations therein, without substantial change, in temperature bringing the dissolved iodine containing, aqueous solution in disseminated form into Contact Withan' inert gas non-con- ;d ensable room temperature to extract the iodinetherefrom, thencontacting the iodineladen with an agent forremoving the iodine. therefrom, and in cyclic manner re-' turning the inert gas to the step of extracting iodinefroIn-the disseminated aqueous solution. I a V '18. The process-of recovering iodine from non-alkaline aqueous solutions containing iodine compounds,w;h i ch comprises liberating the i0 dineefrom its chemical combinations therein, without substantial change in temperaturebringing, the dissolved iodine containing aqueous solution in disseminated form into, contact with a gaseous mixlmre of air andcarbon dioxide to extract the iodine therefrom, and then contacting the iodine- .ladenegasjwith an agentfor removing the iodine therefrom. 1

1 19., The process of recovering iodine from non-alkaline aqueous solutions containing P iodine compounds, which comprises liberating the iodine from its chemical combinations therein, without substantial change in temperature bringing the dissolved iodine containing aqueous solution in disseminated form-into-contact with nitrogen to extract the iodine vtherefrom, and then contacting the iodine-laden gaswith an agent for removing the iodine therefrom. v V

V In testimony whereof, I have hereunto set V co LT'ER W. ones. 

